Method for automatically controlling lighting devices and device for carrying out the method

ABSTRACT

In a method for the automatic control of lighting devices, particularly of a motor vehicle, and a device for implementing the method, the brightness in a specific direction being detected by at least one directional sensor which emits direction signals to a control device, the control device switching on the lighting devices after a minimum time has elapsed. The minimum time begins when the direction signals exceed or drop below a switch-on threshold. The lighting devices are only switched on when the direction signals lie above or below the switch-on threshold during the entire minimum time. To that end, the control device is connected to a timer.

FIELD OF THE INVENTION

The present invention relates to a method and a device for the automaticcontrol of lighting devices, particularly of a motor vehicle.

BACKGROUND INFORMATION

There are numerous devices for the automatic control of lighting devicesof motor vehicles, such as those described, for example, in GermanPublished Patent Application No. 195 23 262. These sensor devicesinclude a global sensor detecting the general light conditions in thevicinity of the vehicle in a non-directional manner, and at least onedirectional sensor detecting the light conditions in the traveldirection in front of the vehicle in a directional manner, as well as acontrol device which controls the lighting devices of the vehicle as afunction of the signals emitted by the sensors. In this context, thelighting devices are switched on, for example, when the global lightsensor reports brightness, but the directional sensor reports darknessas is the case, for instance, in front of a tunnel entrance.

SUMMARY

The method of the present invention may provide that the lightingdevices are first switched on after a minimum time has elapsed whichbegins when the directional signals exceed a switch-on threshold and lieabove this switch-on threshold during the entire minimum time. Usingthis method, bridges may be reliably recognized and distinguished fromtunnels, a disturbing blinking-light effect of the lighting devicesbeing avoided. It may be ensured that the lighting devices are notactivated unnecessarily, and are deactivated again only after theswitch-off delay time has elapsed, or after dropping below a switch-offthreshold.

The lighting devices may be first switched on when the direction signalsconveyed by the directional sensor are rising monotonically,particularly strictly monotonically, during the entire minimum time. Itis thus possible to recognize whether the brightness increases againbefore the minimum time has elapsed, which points to the end of the darkperiod and thus of the bridge.

If the directional sensor has an acquisition cone, pointing in thedirection of travel when in the installed state, with an acceptanceangle less than 90°, a particularly good contrast ratio may result whenthe vehicle is located in front of a dark object such as a tunnel.

If the minimum time is determined in view of the ambient brightness,which is detected by a global sensor, then it may be adjusted optimallyto the ambient conditions.

The minimum time may be determined in view of the speed of the motorvehicle, since on one hand, the lighting devices should be switched onearlier at higher speeds, and on the other hand, short dark sectionslike bridges, for example, are traveled through in a shorter time.

If the minimum time is read from a table in the memory of the controldevice as a function of the ambient brightness and/or the speed, themethod of the present invention may then be implemented in a simplemanner.

The minimum time may be determined as a function of the horizontaldirection in which the motor vehicle is moved and/or the time of dayand/or the place at which the motor vehicle is located. In this manner,it is possible to compensate for effects dependent on the direction oftravel which arise, for example, because, based on the position of thesun, during the evening hours the directional sensor detectssubstantially less brightness in the eastern direction than in thewestern direction and vice versa.

The lighting devices may be controlled with the aid of a timer whichemits time signals to the control device controlling the lightingdevice. It is thus possible to avoid disturbing blinking-light effectswhich come about when traveling through short tunnels and bridges.

An exemplary embodiment of the present invention is explained in detailin the following description and is illustrated in the Figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a device according to the presentinvention.

FIG. 2 illustrates an exemplified signal pattern of the directionalsignal when traveling through a tunnel and a lighting diagram for it.

FIG. 3 illustrates an exemplified signal pattern of the directionalsignal when driving through a bridge.

FIG. 4 illustrates an exemplified signal pattern of the directionalsignal when passing through under a bridge, having a detectionthreshold.

DETAILED DESCRIPTION

A device of the present invention is illustrated schematically in FIG.1. It is made essentially of a control device 10, a global sensor 12, adirectional sensor 14 and a timer T. Control device 10 is also connectedto lighting devices 16 and is able to control them. To that end, controldevice 10 receives direction signals SR from directional sensor 14.

Directional sensor 14 and global sensor 12 are positioned in a motorvehicle, for example, on windshield 18. In this context, the directionalsensor is aligned approximately in the direction of travel and has anacceptance cone Ψ of, for example, 30°. Global sensor 12, in anon-directional manner, measures the ambient brightness in the area ofthe motor vehicle.

If the vehicle is located in front of a tunnel, global sensor 12 conveyssignals to control device 10 which—assuming normal daylight—indicate arelatively high ambient brightness. Directional sensor 14 conveysdirection signals SR to control device 10 which already indicatedarkness.

An exemplary signal pattern for such a case is illustrated at the top inFIG. 2. The vehicle is moving with a speed toward a tunnel and travelsthrough it. In the diagram, direction signals SR of directional sensor14 are plotted over time. A high ordinate value indicates greatdarkness. Moreover, at the bottom of FIG. 2, a lighting diagram isillustrated in which the switch-on and switch-off points of lightingdevices 16 are illustrated.

In the following, the method of the present invention is explained ingreater detail.

The motor vehicle having the device of the present invention istraveling toward a tunnel. Direction signal SR of directional sensor 14rises ever further, since it is becoming “ever darker” in front of thevehicle. At moment T1, direction signal SR exceeds switch-on thresholdSE. Control device 10 now checks whether direction signals SR lie aboveswitch-on threshold SE for the length of minimum time tb. If this is thecase, as illustrated in FIG. 2, then after minimum time tb has elapsed,lighting devices 16 are switched on at moment t2 (FIG. 2, bottom).

In FIG. 3, direction signal SR of directional sensor 14 is again plottedover time. In contrast to FIG. 2, however, in this case the vehicle ispassing through below a bridge. The brightness detected by directionalsensor 14 thereby decreases, which means direction signal SR increasesand exceeds the switch-on threshold at moment Tl. Signal SR is againmonitored during minimum time tb. In this case, however, signal SR hasfallen below switch-on threshold SE before minimum time tb has expired.Because of this, lighting devices 16 are not switched on after minimumtime tb has elapsed.

Lighting devices 16 are switched off again when direction signal SRagain drops below a switch-off threshold SA. It is also possible not toswitch off lighting devices 16 exclusively as a function of directionsignals SR, but in addition to take further signals such as those ofglobal sensor 12 or another device.

In one variation of the invention, after direction signal SR has risenand exceeded switch-on threshold SE, it is possible to check whetherdirection signal SR rises or falls monotonically. This is illustrated inFIG. 4. After the entry of the vehicle into a bridge area, directionsignal SR declines and exceeds switch-on threshold SE. At this momentT1, minimum time tb begins during which it is checked whether directionsignal SR rises further or—as illustrated in FIG. 4—declines againwithin minimum time tb. In this case, lighting devices 16 are notswitched on, although direction signals SR still lie above switch-onthreshold SE after minimum time tb has elapsed.

Moreover, in a further variation, it is possible to evaluate the slopeonly when a further threshold SG is not exceeded. In this variation,direction signal SR exceeds switch-on threshold SE, whereupon minimumtime tb begins to run. If, moreover, direction signal SR exceeds furtherthreshold SG, then lighting devices 16 are switched on after minimumtime tb has elapsed regardless of the profile of the slope, providedthat at this moment, direction signals SR lie above switch-on thresholdSE or further threshold SG.

The slope may also be evaluated in a simple manner, in that afterminimum time tb has elapsed, direction signals SR must lie a specificamount above switch-on threshold SE.

Minimum time tb may be variable. For example, it may be established as afunction of the signals from global sensor 12, so that in the twilightphase in which the ambient brightness is somewhat lower than when thesun is high, it may be selected to be a little shorter. Moreover, it isalso possible to supply signals, for example, from a rain sensor or aGPS or navigation system to control device 10, and to influence minimumtime tb as a function of the location and/or the time of day and/or thetravel direction. In particular, it is possible to convey signals tocontrol device 10 which are a measure for the speed of the vehicle, andminimum time tb may be shortened or lengthened as a function of thesesignals.

It is also possible to use a compass by which the horizontal directionin which the vehicle is moved may be determined. In this case, it ispossible, for example, to shorten minimum time tb when traveling in adirection from east to west in the evening hours when the sun is low inthe west, and to lengthen it in the reverse case.

Control device 10 may also receive weather information, for example, viaa radiocommunication service or the Internet, and evaluate it.

1. A method for automatic control of lighting devices, comprising:detecting a brightness in a specific direction by at least onedirectional sensor which emits direction signals to a control device;switching on the lighting devices by the control device after anexpiration of a minimum time which begins when the direction signals;and one of exceeding and dropping below a switch-on threshold; and areone of above and below the switch-on threshold during the entire minimumtime; and determining the minimum time in view of an ambient brightnessdetected by at least one global sensor.
 2. The method according to claim1, wherein the lighting devices are switched on in the switching on steponly when the direction signals are monotonically one of rising andfalling during the entire minimum time.
 3. The method according to claim1, wherein the lighting devices are switched on in the switching on steponly when the director signals are strictly monotonically one of risingand falling during the entire minimum time.
 4. The method according toclaim 1, wherein the directional sensor detects the brightness in thedetecting step from an acquisition cone which, in an installed state,points in a direction of travel, and which has an acceptance angle thatis at least less than 90°.
 5. The method according to claim 4, whereinthe acceptance angle is less than 70°.
 6. The method according to claim4, wherein the acceptance angle is less than 45°.
 7. The methodaccording to claim 1, wherein the minimum time is determined in thedetermining step in view of a speed of a motor vehicle.
 8. The methodaccording to claim 7, wherein the determining step includes a substep ofreading the minimum time from a table in a memory of the control deviceas a function of at least one of the ambient brightness and the speed.9. The method according to claim 1, wherein the determining stepincludes a substep of reading the minimum time from a table in a memoryof the control device as a function of at least one of the ambientbrightness and a speed.
 10. The method according to claim 1, wherein theminimum time is determined in the determining step as a function of atleast one of a horizontal direction in which a motor vehicle is moved, atime of day and a place at which the motor vehicle is located.
 11. Themethod according to claim 1, wherein the lighting devices are arrangedin a motor vehicle.
 12. A device for automatic control of lightingdevices, comprising: at least a directional sensor configured to detecta brightness in a specific direction; a control device configured toswitch on the lighting devices after an expiration of a minimum timewhich begins when direction signals emitted by the at least onedirectional sensor to the control device: (a) are one of exceeding anddropping below a switch on threshold, and (b) are one of above and belowthe switch on threshold during the entire minimum time; the controldevice configured to determine the minimum time in view of an ambientbrightness detected by at least one global sensor; and a timerconfigured to emit time signals to the control device.
 13. The deviceaccording to claim 12, wherein the device is configured to be arrangedin a motor vehicle.